Changes in material and architectural properties of rat femoral diaphysis during ontogeny in hypophysectomized rats

Alippi, Rosa M.; Olivera, María I.; Huygens, Patricia; Bozzini, Clarisa

doi:10.1007/s00580-005-0543-9

Cited by 5 publications

(4 citation statements)

References 23 publications

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“…The cortical bone of the HT rat thus appears as a bone with a higher than normal strength and stiffness relative to body weight, probably due to improvement of bone material quality. Similar conclusions have been arrived for cortical bone of hypophysectomized rats [12], which suggest that hypothyroidism and hypopituitarism may affect bone biomechanics through a common operative mechanism which is associated to growth retardation.…”

Section: Discussionsupporting

confidence: 64%

“…Because mineral composition, particle size and distribution are not always the same, the properties of the crystals should also be considered as one of the factors contributing to material properties, when discussing the ability of bone to resist fracture [24]. The femoral shaft of the hypophysectomized rat is characterized by its high mineral density and its unusual large modulus of elasticity in spite of cessation of linear growth [12]. Both collagen maturation and cross-linking and the degree of mineralization of bone have been found to be increased in the hypophysectomized rat femur [25].…”

Section: Discussionmentioning

confidence: 99%

“…We have recently shown that [12], although, the femur size of the hypophysectomized rat does not enlarge with age, its weight and its calcium mass (femur bone mass) increase significantly. From the biomechanical point of view, the bone markedly increases its intrinsic and extrinsic stiffness.…”

Section: Introductionmentioning

confidence: 99%

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Biomechanical performance of diaphyseal shafts and bone tissue of femurs from hypothyroid rats

Conti

Martínez

Olivera

et al. 2009

Endocr

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The bone changes in hypothyroidism are characterized by a low bone turnover with a reduced osteoid apposition and bone mineralization rate, and a decreased osteoclastic resorption in cortical bone. These changes could affect the mechanical performance of bone. The evaluation of such changes was the object of the present investigation. Hypothyroidism was induced in female rats aged 21 days through administration of propylthiouracil in the drinking water for 70 days (HT group). Controls were untreated rats (C group). Right femur mechanical properties were tested in 3-point bending. Structural (load bearing capacity and stiffness), geometric (cross-sectional area and moment of inertia) and material (modulus of elasticity) properties were evaluated. The left femur was ashed for calcium content determination. Plasma T(4) concentration was significantly decreased in HT rats. Body and femur weight and length in HT rats were also reduced. Femoral calcium concentration in ash was higher in HT than in C rats. However, the femoral calcium mass was significantly lower in HT than in C rats because of the reduced femoral size seen in the former. The stiffness of bone material was higher in HT than in C rats, while the bone geometric properties were significantly lower. The "load capacity" was between 30 and 50% reduced in the HT group, although, the differences disappeared when the values were normalized per 100-g body weight. The lowered biomechanical ability observed in the femoral shafts of HT rats seems to be the expression of a diminished rate of growth. Qualitative alterations in the intrinsic mechanical properties of bone tissue were observed in HT rats, probably because the mineral content and the modulus of elasticity were positively affected. The cortical bone of the HT rat thus appears as a bone with a higher than normal strength and stiffness relative to body weight, probably due to improvement of bone material quality due to an increased matrix calcification.

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Section: Discussionsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 99%

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Biomechanical performance of diaphyseal shafts and bone tissue of femurs from hypothyroid rats

Conti

Martínez

Olivera

et al. 2009

Endocr

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“…Study of ontogenetic changes in mechanical properties during skeletal growth furthers understanding of how bone geometric and elastic properties are adapted to morphology, function, ageing, pregnancy, and pathological conditions (Currey and Butler, 1975; Ekeland et al, 1982; Keller et al, 1985; Reid and Boyde, 1987; Stein, 1988; Currey et al, 1996; Hara et al, 1998; Currey, 2001; Ruff, 2003; Alippi et al, 2005; Havill et al, 2006; Elsalanty et al, 2008). Thus, two fundamental questions need satisfactory answers: [1] What is the pattern of the variation in bone material properties?…”

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confidence: 99%

Regional, ontogenetic, and sex‐related variations in elastic properties of cortical bone in baboon mandibles

Wang¹,

Ashley²,

Dechow³

2009

American J Phys Anthropol

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Understanding the mechanical features of cortical bone and their changes with growth and adaptation to function plays an important role in our ability to interpret the morphology and evolution of craniofacial skeletons. We assessed the elastic properties of cortical bone of juvenile and adult baboon mandibles using ultrasonic techniques. Results showed that, overall, cortical bone from baboon mandibles could be modeled as an orthotropic elastic solid. There were significant differences in the directions of maximum stiffness, thickness, density, and elastic stiffness among different functional areas, indicating regional adaptations. After maturity, the cortical bone becomes thicker, denser, and stiffer, but less anisotropic. There were differences in elastic properties of the corpus and ramus between male and female mandibles which are not observed in human mandibles. There were correlations between cortical thicknesses and densities, between bone elastic properties and microstructural configuration, and between the directions of maximum stiffness and bone anatomical axes in some areas. The relationships between bone extrinsic and intrinsic properties bring us insights into the integration of form and function in craniofacial skeletons and suggest that we need to consider both macroscopic form, microstructural variation, and the material properties of bone matrix when studying the functional properties and adaptive nature of the craniofacial skeleton in primates. The differences between baboon and human mandibles is at variance to the pattern of differences in crania, suggesting differences in bone adaption to varying skeletal geometries and loading regimes at both phylogenetic and ontogenetic levels.Keywords craniofacial skeleton; biomechanics; function; adaptation; Micro-CT; primate Elastic properties and their variations in individuals are important for understanding bone adaptations and quality at the tissue level (Dechow et al., 1992(Dechow et al., , 1993Dechow and Hylander, 2000; Schwartz-Dabney and Dechow, 2003;Wang and Dechow, 2006;Wang et al., 2006; Rapoff et al., 2008). They are especially indispensable for exploring the biomechanics and adaptation of primate skulls using Finite Element Analysis (FEA) (Strait et al., 2005(Strait et al., , 2009Wang and Dechow, 2006;Wang et al., 2006; Rayfield, 2007). We have * Please send page proofs and direct correspondence to: Dr Qian Wang, Division of Basic Medical Sciences, Mercer University School of Medicine, 1550 College Street, Macon, GA 31207. Phone:478-301,4043; Fax: 478-301,5489; wang_q2@mercer.edu NIH Public Access Author ManuscriptAm J Phys Anthropol. Author manuscript; available in PMC 2011 April 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript systematically collected elastic properties from the craniofacial skeletons of three species including modern humans (crania and mandibles), macaques (crania), and baboons (crania) (Peterson, 2002; Peterson and Dechow, 2003; Dechow, 2002a, 2003;Dechow, 2006, Wang et al, 2006)...

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Biomechanical properties of the mid-shaft femur in middle-aged hypophysectomized rats as assessed by bending test

et al. 2012

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Both stiffness and strength of bones are thought to be controlled by the "bone mechanostat". Its natural stimuli would be the strains of bone tissue (sensed by osteocytes) that are induced by both gravitational forces (body weight) and contraction of regional muscles. Body weight and muscle mass increase with age. Biomechanical performance of load-bearing bones must adapt to these growth-induced changes. Hypophysectomy in the rat slows the rate of body growth. With time, a great difference in body size is established between a hypophysectomized rat and its age-matched control, which makes it difficult to establish the real effect of pituitary ablation on bone biomechanics. The purpose of the present investigation was to compare mid-shaft femoral mechanical properties between hypophysectomized and weight-matched normal rats, which will show similar sizes and thus will be exposed to similar habitual loads. Two groups of 10 female rats each (H and C) were established. H rats were 12-month-old that had been hypophysectomized 11 months before. C rats were 2.5-month-old normals. Right femur mechanical properties were tested in 3-point bending. Structural (load-bearing capacity and stiffness), geometric (cross-sectional area, cortical sectional area, and moment of inertia), and material (modulus of elasticity and maximum elastic stress) properties were evaluated. The left femur was ashed for calcium content. Comparisons between parameters were performed by the Student's t test. Average body weight, body length, femur weight, femur length, and gastrocnemius weight were not significantly different between H and C rats. Calcium content in ashes was significantly higher in H than in C rats. Cross-sectional area, medullary area, and cross-sectional moment of inertia were higher in C rats, whereas cortical area did not differ between groups. Structural properties (diaphyseal stiffness, elastic limit, and load at fracture) were about four times higher in hypophysectomized rats, as were the bone material stiffness or Young's modulus and the maximal elastic stress (about 7×). The femur obtained from a middle-aged H rat was stronger and stiffer than the femur obtained from a young-adult C rat, both specimens showing similar size and bone mass and almost equal geometric properties. The higher than normal structural properties shown by the hypophysectomized femur were entirely due to changes in the intrinsic properties of the bone; it was thus stronger at the tissue level. The change of the femoral bone tissue was associated with a high mineral content and an unusual high modulus of elasticity and was probably due to a diminished bone and collagen turnover.

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Changes in material and architectural properties of rat femoral diaphysis during ontogeny in hypophysectomized rats

Cited by 5 publications

References 23 publications

Biomechanical performance of diaphyseal shafts and bone tissue of femurs from hypothyroid rats

Biomechanical performance of diaphyseal shafts and bone tissue of femurs from hypothyroid rats

Regional, ontogenetic, and sex‐related variations in elastic properties of cortical bone in baboon mandibles

Biomechanical properties of the mid-shaft femur in middle-aged hypophysectomized rats as assessed by bending test

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